It is important for Japan to strengthen its economic and security relations with India, which has the world's second largest population at over 1.2 billion and is enjoying economic growth.

However, Japan, being the only atomic-bombed country, must not play any role in helping making the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) a mere facade.

Prime Minister Shinzo Abe and his Indian counterpart Narendra Modi agreed in principle that the two countries will sign an atomic energy agreement opening the way for India to import nuclear plant-related equipment from Japan.

The NPT allows only five nuclear powers -- the United States, Russia, Britain, France and China -- to possess such weapons of mass destruction while permitting other countries to use atomic energy purely for peaceful purposes. India criticizes the NPT as an unequal treaty and refuses to join it.

This is the first time for Japan to sign an atomic energy agreement with a non-party to the NPT. Even though India is supposed to use nuclear-related equipment it will import from Japan strictly for peaceful purposes, Japan's cooperation with India, which continues to possess nuclear weapons outside the framework of the NPT, could go beyond the limit set by the treaty.

The latest agreement does not clarify how to secure the peaceful use of Japan's atomic energy technology in India.

Prime Minister Abe appreciated a moratorium on nuclear tests that India announced in 2008, and emphasized that the agreement will ensure Japan's cooperation with India be limited to peaceful purposes.

However, his assertion is without sufficient basis. Abe reportedly told Modi during the latest summit meeting that Japan would immediately suspend its cooperation if New Delhi were to conduct another nuclear test. However, it remains to be seen whether that point will be clearly mentioned in the bilateral agreement.

The two countries have also delayed a conclusion on how to reprocess spent nuclear fuel at atomic power stations that will be built using devices and materials imported from Japan.

The two countries appear to have hastily reached a broad agreement on atomic energy cooperation without working out its details.

In India, 21 nuclear reactors are in operation, and the country has set a goal of expanding the power generation capacity of its atomic power stations to nearly 11 times the current level by 2032.

The United States signed an atomic energy agreement with India in 2008 in a bid to enter this potentially huge nuclear market. Since then, France, Russia, Canada, South Korea and other countries have signed similar pacts with India.

Japan launched negotiations with India on such an agreement in 2010 under the previous administration led by the now largest opposition Democratic Party of Japan as the government regarded exports of nuclear plants as part of its economic growth strategy. Japan was under pressure from the United States and France to sign an atomic power agreement with India because these countries would be affected by Japan's failure to conclude such an accord as atomic energy companies in these three countries are cooperating increasingly closely. The Abe government also apparently aims to keep China in check by strengthening Japan-India nuclear cooperation.

The government has struggled to achieve a balance between its position as the only atomic-bombed country and its realistic benefits of helping Japanese companies enter the Indian nuclear energy market and keeping China in check. If guaranteeing that Japan-made nuclear-related equipment will be used purely for peaceful purposes in India is a key to achieving this balance, Japan should clarify this when the two countries sign the agreement.

Japan, which is supposed to play a leading role in nuclear disarmament, must not give tacit approval to India's possession of nuclear arms or facilitate nuclear proliferation. If Japan were to do so, the international community would lose confidence in Tokyo's diplomacy aimed at ridding the world of nuclear weapons and Japan's influence in this regard would be lost.